[omii]

I purchased this TM300XRX in December 2014 making it 18 months old. It was maintained to spec. After 5 hours and then every 10 after that. It is stored in a heated/cooled garage.

From the beginning the gear selector would randomly grind (infrequently, 1 out of 20~40 gear changes). When it grinded I'd just put it back to neutral and then back to gear (forward or reverse) and it'd be fine.

I just went to perform seasonal tasks, changing coolant, oil, spark plug, dipped air filter in non flammable cleaner, tightening all bolts in sight, battery on maintainer and fresh shell 94oct.

Took about 7 attempts to start it but it finally started and idled. I let it idle for 10min, revving a bit.

It's still grinding randomly. Also, now it seems to have a pronounced whine as it picks up speed. The kind of sound gears make when they're too close or far apart. Basically it sounds like a mix between any full size car that is well past needing an oil change (like 15k miles) and/or more like exactly what a radio controlled car sounds like accelerating and decelerating.

Any ideas on what would make the gear selector (forward, neutral, reverse) grind? Or anyone know what this new sound might be that goes higher in pitch as it accelerates? My small engine guy thinks the clutch plates might need spacing adjustment. I'm really interested in this new radio controlled car sound it has now.

I don't know how to tell exactly how many miles or hours there are but I do keep pretty close hourly mental notes. It has, despite being 18 months old, less than 40 hours. My notes say 37 hours. We just never have time to drive.

Thanks for any tips on this Yamaha scooter in disguise!

Edit:

Forgot one more question that might have some bearing. In the manual in specification (page 11) under engine it says lubrication oil: 15W 40s/f. Then on page 17 and after in the maintenance section it says remove oil and replace with 30oz of 10W 40... I put in Rotella T 15W 40 diesel grade oil. I have 2 cars so I totally forgot if I put 15W40 in it previously or 10W40.

Does anyone know what the right oil is? If I put the thicker 15W40 in and it should have 10W40, could that cause the noise? Harm the engine? I ran it tonight about 20min. 10 in idle, 10 up and down the street. Grinded once and whined on accel/decel.